The latest results from the 2021 Global Burden of Disease (GBD) study published in The Lancet on May 18 predict that between 2022 and 2050, global life expectancy for men will increase by 4.9 years, and for women by 4.2 years.
Countries with lower life expectancies are projected to see the largest increases, contributing to a convergence in life expectancies across different regions. This trend is largely driven by public health interventions that effectively prevent cardiovascular diseases, COVID-19, as well as a range of infectious diseases, maternal and neonatal conditions, nutritional deficiencies (CMNN), thereby improving survival rates.
The study indicates a continued shift in disease burden towards non-communicable diseases (NCDs) such as cardiovascular diseases, cancer, chronic obstructive pulmonary disease, and diabetes, along with exposure to NCD-related risk factors like obesity, hypertension, suboptimal diet, and smoking, which will have the greatest impact on the disease burden of the next generation.
As the burden of disease continues to transition from CMNN to NCDs, from years of life lost (YLL) to years lived with disability (YLD), it is expected that more people will live longer, but with more years of ill health. Global life expectancy is projected to increase from 73.6 years in 2022 to 78.1 years in 2050 (an increase of 4.5 years). Global Healthy Life Expectancy (HALE) - the average number of years a person can expect to live in good health - is expected to rise from 64.8 years in 2022 to 67.4 years in 2050 (an increase of 2.6 years).
To arrive at these conclusions, the study forecasted mortality rates, YLL, YLD, Disability-Adjusted Life Years (DALYs), life expectancy, and HALE for 204 countries and territories from 2022 to 2050 based on specific causes.
"In addition to the overall increase in life expectancy, we also found that the gap in life expectancy between different regions will narrow," said Chris Murray, Chair of Health Metrics Sciences at the University of Washington and Director of the Institute for Health Metrics and Evaluation (IHME). "This suggests that while health inequalities between the highest and lowest income regions will persist, the gap is narrowing, with the largest growth expected in sub-Saharan Africa."
Murray added that the greatest opportunity to accelerate the reduction of the global disease burden is through interventions aimed at preventing and mitigating behavioral and metabolic risk factors.
These findings build upon the 2021 GBD Risk Factors study also published in The Lancet. This accompanying research found that since 2000, the total years lost due to poor health and premature death caused by metabolic risk factors have increased by 50% (measured in DALYs).
The study also presents various scenarios to compare the potential health outcomes if different public health interventions could eliminate key risk factors' population exposure by 2050.
"We predict significant differences in global DALY burden between different alternative scenarios to understand what has the greatest impact on overall life expectancy data and DALY predictions," said Stein Emil Vollset, first author of the paper and Head of the GBD Collaborator at the Institute of Public Health, Norway. "Globally, compared to the 'reference' (most likely) scenario, the 'improve behavior and metabolic risks' scenario is expected to reduce the disease burden by 13.3% by 2050."
The authors also designed two additional scenarios: one focusing on a safer environment and the other on improving child nutrition and vaccination.
Amanda E. Smith, Assistant Director of the Forecasting Department at IHME, stated, "While the greatest impact on the global DALY burden comes from the 'improve behavior and metabolic risks' scenario, we also predict that the 'safer environment' and 'improve child nutrition and vaccination' scenarios will reduce the disease burden. This suggests the need to continue progress and allocate resources in these areas, potentially accelerating progress by 2050."
Murray concluded, "We have an opportunity to shape the future of global health by controlling metabolic and dietary risk factors, especially those related to behavior and lifestyle factors such as high blood sugar, high body mass index, and hypertension."
For more information, refer to the related paper: https://doi.org/10.1016/S0140-6736(24)00685-8
